1. Gillian Byrne Memorial University of Newfoundland

2. Research process & definitions Hypothesis construction Sampling Statistical significance Variables Descriptive statistics Popular inferential statistical analyses 3. Develop hypotheses Identify target population Select random sample Test hypotheses using statistical analyses Determine the likelihood that: The performance of the sample group reflects the population and is not due to sampling error The performance of the sample is not due to chance (statistical significance) 4. Population: the entire collection of units you are interested in Sample: subset of that population A sample is used to infer conclusions about the population 5. A parameter is a characteristic of an entire population A statistic is a characteristic derived from a sample Statistics are used to estimate unknown parameters The average Canadian uses the Internet 5 times a week 6. Descriptive statistics describe the data Example: the average age of librarians in the study was 44 Inferential statistics attempts to infer conclusions to a wider population The results of the survey show that Canadian Librarians are aware of Evidence-based Practice If I sample 4 grapes and they all taste good, can I conclude the bunch of grapes is good? 7. Hypothesis are statements of what you want to prove (or disprove) Good Hypotheses are: Measurable Simple Answerable with the research method/data Compatible with the natural order of the world 8. Measurable? 1-5 are measureable if proper definitions are provided 6 is not measureable better librarians? 9. Simple? Terms like feel, understanding are ambiguous Original #4: Does institution type affect the knowledge of EBP? Rephrase of #4: Does institution type affect librarians score on the EBP Understanding Test? Answerable? Measuring two distinct things perception and performance - with two distinct research methods (survey and test) 10. Scientific method attempts to disprove the null hypothesis rather than prove the hypothesis. Why? Research Question Does institution type affect librarians score on the EBP Understanding Test? Hypothesis Institution type affects librarians score on the EBP Understanding Test Null hypothesis Institution type does not affect librarians score on the EBP Understanding Test 11. Type I error False positive; observing a difference when there is not one Type II error False negative; observing no relationship when there is one False positives are considered a more serious result, so the null hypothesis is tested 12. Random SamplingProbability Sampling Stratified Random Sampling Cluster Sampling Non-probability Sampling Convenience Sampling Purposive Sampling 13. Sampling technique in which every member of a population has an equal chance to get picked for the sample To obtain a probability sample, the population must be identifiable A probability sampling technique must be used for inferential statistics 14. Random Sampling selecting subjects from a population using unpredictable methods Stratified Random Sampling Dividing a sample into sub-populations, then randomly selecting subjects from each sub-population Cluster Sampling Dividing a population into clusters, then randomly selecting a sample of these. All observations in the selected clusters are included in the sample 15. Sampling Technique? Stratified random sampling was used to ensure that all types of librarians would be represented Probability Sample? It is a random sample of all librarians who belong to CLA cant be generalized to all Canadian librarians 16. Central Limit Theorem: states that the larger the sample, the more likely the distribution of the means will be normal, and therefore population characteristics can more accurately be predicted No magic number! Sample size dictates Confidence Intervals 17. Random samples eliminate bias, but they can still be wrong Sampling Variability: If you select many different samples from the same population, a statistic could be different for every different sample Confidence Intervals reflect how confident a researcher is that the findings are correct and repeatable 18. CI are traditionally set at 95% or 99% (i.e., Im 95% sure the results are will fall into range X) Large CI usually indicate sampling problems Lancet Study on Iraqi deaths: Used cluster sampling to ascertain the Iraqi death toll up until 2004 was 654,965 plus or minus 291,186! 19. Librarians who have heard of EBP by Institution Type If the sample size is 210 people and the margin of error (CI) is plus or minus 3.1 percentage points, 19 times out of 20, do more academic librarians know about EBP than special librarians? 20. Statistical significance tells you how unlikely a result is due to chance probably true Significance tests denote how large the possibility is that you are committing a type I error More academic librarians are aware of EBP than public librarians, but is the difference in the numbers real or simply due to chance? 21. Statistical significance is calculated as a p-value that ranges between 0-1 .05 is the conventional cut-off point for significance (p>.05 = significance; p